The story starts when a kid comes out of the school bathroom with toilet paper dangling from his or her waistband. Write a book about how a character has been living a very sheltered, very dangerous life.
Smoke, Fog, and Haze: Write about not being able to see ahead of you. Mechanical: Think of gears, moving parts, machines. Write about how the only reason your character is alive is because of a test device implanted around their heart. What happens in this pivotal moment will drive the story and have a deep impact on the main character.
When one kid proves to be way more than expected, they have to help them understand exactly what they can do — and stop them from doing something that could be dangerous.
Your character is of a very noble household and can barely sleep each night. Did you try again or give up completely?